1. Field of the Invention
This invention relates to air vehicle nose cones that are collapsible for storage, deploy at launch to protect the vehicle's dome and reduce drag and release to allow the vehicle seeker to image the scene during terminal flight maneuvers. The nose cones are particularly applicable to supersonic missiles and smart projectiles to protect the seeker dome and reduce drag.
2. Description of the Related Art
Air vehicles such as missiles and more recently some smart projectiles include seekers that guide them to their target. These seekers typically include IR sensors and may also include visible sensors or RF antennas. These sensor components are protected from the atmosphere by a dome. In order to allow electromagnetic radiation of the desired wavelength to pass through the dome, the dome must be constructed of certain materials and with a certain blunt shape (e.g. hemispheric). These dome materials are susceptible to damage during normal pre-flight handling. Furthermore, the optical properties of these dome materials tend to degrade during flight through the atmosphere. In addition, the blunt nose of the dome produces considerable aerodynamic drag particularly at supersonic speeds.
To protect the vehicle ‘pre-flight’, a conformal hard cover is placed over the dome and the vehicle is placed inside a tube for ground, sea or air-based launch. At launch, meaning just prior to to just after launch, the cover is blown off of the vehicle using pyro charges. One design uses an expanding mandrel that pushes the cover off shearing rivets that hold the cover to the vehicle. In another design, a squib is fired that opens the cover like a clam shell allowing the two halves to split apart starting at the tip and fall away from the vehicle. This approach provides no protection of the dome during atmospheric flight or reduction in drag from launch to the point where the seeker activates to image the scene.
In certain space-based applications such as Exoatmospheric Kill Vehicle (EKV) and Standard Missile 3, sensor packages are provided for space-based imaging. Because sensing is only performed in space a dome is not required to protect the sensor, hence is not included. The Standard Missile 3 and the carrier vehicle for the EKV include a pointed nose cone that protects the sensor packages during atmospheric flight and reduces drag. Once in space, the nose cone is jettisoned to allow the sensor packages to operate.